Field of the Invention
The present invention relates to an image forming apparatus such as an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, and an LED printer), a facsimile device for forming an image on a recording medium by using an electrophotographic image forming method, a process cartridge detachably attachable to an image forming apparatus, and a developing apparatus incorporated into an image forming apparatus or a process cartridge.
Description of the Related Art
A developing apparatus used for an image forming apparatus includes a configuration for supplying a toner, which is consumed according to image formation, to a developing apparatus for performing developing process from a toner bottle accommodating a toner. In particular, there is a configuration having a toner bottle and a pump as a developer pressurizing supply mechanism, and supplying a toner to a developing apparatus from the developer pressurizing supply mechanism according to an increase in an internal pressure caused by a contraction of this pump.
However, in a configuration for supplying toner by using such pump, a change occurs in an internal pressure in the developing apparatus during toner supply, and accordingly, the internal pressure in the developing apparatus during the toner supply becomes larger than the air pressure outside of the device, so that the toner may spout out to the outside of the developing apparatus. Therefore, the method for preventing this has been disclosed in the past.
For example, Japanese Patent Laid-Open No. 2012-93736 discloses a configuration for supplying a toner to a developing apparatus via a conveying chamber having a conveying path from a pump accommodation unit having a pump, wherein the configuration prevents the toner from spouting out into the conveying chamber and has a filter for allowing air ventilation to the outside. With this configuration, air ventilation to the outside is conducted, so that the internal pressure is prevented from increasing, and the toner is prevented from spouting out to the outside of the developing apparatus.
However, in a configuration using a filter to prevent the internal pressure from increasing and prevent the toner from spouting out, e.g., the configuration described in Japanese Patent Laid-Open No. 2012-93736, the filter may be clogged due to a usage for a long period of time even if various kinds of countermeasures are taken. In a case when the filter is clogged, the air ventilation function of the filter is lost, and the internal pressure in the developing apparatus increases, and the toner spouts out from the developing apparatus, and the toner scatters in the image forming apparatus, and a sheet is smeared, and this may lead to a reduction in the quality of the image.